Starting this year, all Nintendo games rated CERO C and up (that's 15+) will be packaged with black boxes.
Nintendo announced the change shortly before the release of Zangeki no Reginleiv, Nintendo's first "M" rated (well, M equivalent) game in Japan. Previously, CERO C (15+), D (17+), and the rare Z (18+) used standard white covers. CERO C games include Ghost Squad, Disaster: Day of Crisis and WWE 2008 Smackdown vs. Raw. Onechanbara: Bikini Zombie Slayers, No More Heroes, and currently every Resident Evil game on the Wii.